A wireless power transmission or a wireless energy transfer refers to a technology for wirelessly transferring electric energy to desired devices. In the 1800's, an electric motor or a transformer employing the principle of electromagnetic induction has been extensively used and then a method for transmitting electrical energy by irradiating electromagnetic waves, such as radio waves or lasers, has been suggested. Actually, electrical toothbrushes or electrical razors, which are frequently used in daily life, are charged based on the principle of electromagnetic induction. Until now, the long-distance transmission using the magnetic induction, the resonance and the short-wavelength radio frequency has been used as the wireless energy transfer scheme.
Among the above wireless power transmission technologies, a wireless power transmission technology based on magnetic resonance has been recently spotlighted. The wireless power transmission technology based on the magnetic resonance is a technology of inducing an electromagnetic field to transmit power between a receiver and a transmitter that are set in a resonance state, which is suitable for long-distance power transmission.
Meanwhile, there is a scheme under the discussion as a main application field of the wireless power transmission based on the magnetic resonance. According to the scheme, a transmitter is mounted on the ceiling or the wall of a building, and a receiver is installed in a mobile appliance such as a cellular phone, so that a user can charge the mobile appliance without separately connecting a power cable only if the user stays in the interior having a wireless power transmitter installed therein.
However, recently, most of mobile appliances are equipped with touch panels or touch screens. When the mobile appliances for touch detection are charged in wireless, interference between a signal used for wireless power transmission and a signal used for touch detection occurs, so that an erroneous operation may occur in the touch detection.